Humans are built to thrive on Earth, but even a yearlong round-trip mission to Mars could pose major medical risks. If we want humans to colonize the solar system, we may have to fundamentally alter our biology and become cyborgs.

That's the argument put forward by Smithsonian National Air and Space Museum senior curator Roger Launius, who believes unmodified humans won't be able to survive the unforgiving off-world environment. Between cosmic radiation, low gravity levels, and the constant threat of running out of the most basic resources like water or oxygen, the challenge might be too great for humans as they are now, which raises the question of using tactical mechanical enhancements to create cyborg colonists.

Of course, what one means by "cyborg" is open to some discussion. Launius considers anyone with pacemakers and cochlea ear implants to fit the basic definition - which he says means he himself is a cyborg. So somewhere between a sturdier pacemaker and human brains in robotic bodies lies the right balance for these cyborg astronauts, and Launius argues we need to start seriously investigating this topic.

The idea has been floating around for at least fifty years, when Manfred Clynes and Nathan Kline publish "Cyborgs and Space" in 1960. The paper challenged the prevailing - and still common today - notion that humans should seek to replicate their entire Earth environment as they head into space. Instead, they wrote, space explorers must accept the necessity of adapting themselves to the strange new environment of outer space, at least if they're planning on staying away from Earth for extended periods.

NASA actually explored this possibility to some extent in the 1960s, but they abandoned it around the same time unmodified humans Neil Armstrong and Buzz Aldrin were setting foot on the Moon. Part of the problem was that the technology didn't yet exist for them to really pursue the idea, but Launius also suspects NASA was scared off by the ethical quandaries the idea raises.

That's a main part of the debate he's hoping to kickstart:

"It does raise profound ethical, moral and perhaps even religious questions that haven't been seriously addressed. We have a ways to go before that happens."

What he and other ethicists who have considered the topic have generally concluded is that there needs to be sufficient justification for modifying people into something that isn't entirely human. The justification, as Launius sees it, is the hope of becoming a multi-planetary race, and perhaps setting the stage for eventually spreading out into the stars, a goal recently championed by Stephen Hawking.

The opportunity to truly leave Earth behind and expand humanity beyond its evolutionary home is a tantalizing possibility, and one that seems to go some way to making the cyborgization of colonists palatable. Of course, it will then have to be left to those on Earth and in space as to whether it's really humanity that's conquering outer space, and whether the "true" humans ever left Earth at all.